Setterguy you shared with us pictures of your pond covered in some sort of algae and then it disappeared. It undoubtedly settled to the bottom and started to decay. Big clods of dead and decaying algae (organics) will float to the surface and can look just like that. I found two online articles, both in FLorida where reports of floating 'feces' alarmed the public but on review and testing of the water quality and the clods it was decided it was not feces after all.
It fits with the description of your massive algae collapse that some floating decaying organics may resurface?
Maybe that isn't what this is but outside of Bigfoot using your pond as a latrine, I'm hoping it is just good old organic debris.
here is one article. I'd love to know what sort of suction rig can suck up that organic material so well. Sign me up for one of those vacuums!!
